The present invention disclosed herein relates to a supporting unit, and more particularly, to a supporting unit including a heater.
Recently, as semiconductor devices are highly integrated, a unit area of one chip becomes smaller and accordingly, the critical dimension (CD) of a circuit line width is reduced. Therefore, a photolithography process for implementing a pattern, which is used for forming a circuit on a semiconductor substrate, becomes important. The photolithography process includes an application process for applying a photoresist on a substrate, an exposure process for irradiating light on the photoresist, and a development process for partially removing the photoresist according to an exposed pattern. Such an application process, exposure process, and a development process include a bake process for heating a semiconductor substrate.
Examples of the bake process include a soft bake process for alleviating a stress occurring when a photoresist is applied and a hard bake process for chemically stabilizing an exposed portion after an exposure process is performed.
As patterns formed on a substrate are miniaturized gradually, uniformly heating a substrate and maintaining a temperature during a bake process for heating the substrate at a predetermined temperature may service as important factors to control the CD.